Gas burner control mechanism



Dec. 11, 1951 c. M. MAYER EIAL. 2,577,787

GAS BURNER CONTROL MECHANISM 3 Sheets-Sheet l Filed-April 3, 1950 r M aw m w M M mtw ca% y 5 I. Ill-Ill Ill |llll|lln Dec. 11, 1951 c. M. MAYERETAL 2,577,787

GAS BURNER CONTROL MECHANISM Filed April 3, 1950 3 Sheets-Sheet 2 i (1 Iw W IN V EN TORS Lj y Charles M Mayer Dec, 11, 1951 Filed April 3, 1950C. M. MAYER ETAL GAS BURNER CONTROL MECHANISM a Sheets-Sheet 5 LINE IA09 zlll v v 5'4 '1 .57 80 86 .9 g "I 27 83 Z J mw W IINVENTORSC'hczr/es MMa yer 9 John M. Hoff Patented Dec. 11, 1951 Gas-BURNERCONTROL Macnmsm Charles M. Mayer and John Hofl, Mansfield,

Ohio, assignors to The Tapl an Stove Company, Mansfield, Qhio, acorporation of Ohio Application April 3, 1950, Serial No. 153.664

This invention relates to an automatic electric 11 Claims. (Cl. l61-9)ignition and control mechanism for cooking range burners using gaseousfuel. It is especially designed and adapted for automatically ignitingand controlling the operation of oven burners in cooking ranges; but itmay be used equally well to control the operation of other gaseous fuebumers. It may be used in conjunction with a time control mechanism orindependently thereof as desired.

The mechanism is designed for use. with a main gaseous fuel burner whichis adapted to be ignited by a constantly burning gaseousfuel pilotburner. As long as the pilot burner is ignited it is immaterial whetheror not the main burner burns constantly. It may be extinguished for somereason but it will be promptly re-ignited by the pilot burner if fuel issupplied thereto. 'But if the pilot burner is extinguished for anyreason while the main control valve is still open to supply 2 tion. Atother times the supply. of gas to both the main burner andv the pilotburner is cut oil .by a main control valvewhich is interposed in a anismgas will flow through a small branch congas to the main burner a verydangerous situation sometimes arises. Let us assume that both the pilotburner and the main burner are extinguished during operation for somereason. Gas can then flow to the main burner but since the pilot burneris extinguished the main burner will not be ignited and unburned gaswill accumulate in the oven which may violently explode when an attemptis made to ignite either the main or pilot burner. This is likewise trueif gas to the main burner is cut off by the main control valve when theoven is not in use and the constantly burning pilot burner becomesextinguished for any reason. It

- has been found by experience that both the pilot burner and the mainburner are frequently extinguished during use while the main controlexplosion therefrom in the event the pilot'burner is extinguished forany reason while the control valve is still set to supply gas to themain burner, we provide in our improved apparatus safety controlmechanism by which the supply of gas to both the main burner and thepilot burner is completely out off, independently of the main controlvalve, in the event the pilot burner is extinguished for any reasonwhile the main gas control valve is open.

Our improved apparatus includes a main gaseous fuel burner by which theoven in a cooking range is heated. The main burner is adapted to beignited'by a gaseous fuel pilotburner which burns only during the timethe oven is in operaduit directly to the pilot burner; and through themain conduit and a standard thermostatically operated oven temperaturecontrol valve to the main burner. A normally open master control switchwhich is operatively associated with the main control valve is arrangedto be closed by the opening of the main control valve and to be openedby the closing of the main control valve. The closing of the mastercontrol switch, as the main control valve is opened to supply gas to theburners, energizes through a normally closed thermostatically operatedswitch an electric resistance ignition element and a solenoid which isoperatively connected to the safety control valve mechanism. Theenergization of the solenoid causes it to operate the safety controlvalve mechanism to permit the flow of gas to the pilot burner whilecutting off the supply of gas to the main burner. The pilot burner isignited by the electric ignition element and projects a flame against athermostatic element, which controls the operation of the normallyclosed switch, and against a thermo couple which is operativelyconnected to the safety control valve mechanism. After the thermostaticelement becomes heated it opens the normally closed switch whichdeenergizes the electric ignition element and the solenoid. As-soon asthe solenoid is de-ener'gized the safety control mechanism isautomatically operated by spring means to supply gas to the main burnerthrough the oven temperature control valve. The main burner is thenignited by the pilot burner. The thermocouple, as long as it 'is heatedby the pilotburner, maintains the safety control valve mechanism incondition to supply gas to both the main burner and the pilot burner.

reason the thermocouple will immediately cool and allow the safetycontrol valve mechanism to automatically cut off thesupply of gas toboth the main burner and the pilot burner. As an example of the mannerof operation of the apparatus, let us assume that during operation thepilot burner is suddenly extinguished, for instance, by a momentaryfailure of the gas supply from the maniately cools, allowing the safetycontrol valve mechanism to cut oil communication between the manifoldand both the main burner and the pilot burner. The main control valve isstill open and the master switch closed. Then after the thermostaticelement has cooled, closing the normally closed switch, which ismaintained open by the thermostatic element during normal operation ofthe oven, the electric ignition element and the solenoid are againenergized. The energization of the solenoid will cause it to operate thesafety control valve mechanism to establish communication between themanifold and the pilot burner only. Then when gas is again available thepilot burner will be ignited and reestablish normal operation of theoven as previously described. In the event of a power failure duringnormal operation of the oven, the main burner will continue to operatenormally under the control of the oven temperature regulator valve untilthe burner is turned off by the main control valve, assuming of coursethat the pilot burner continues to burn. In the event of a power failurebefore gas is turned on by the main control valve, the

pilot burner can be manually ignited as will be hereinafter explained.The supply of gas to both the'main burner and the pilot burner will thenbe controlled by the pilot burner through the thermocouple and safetycontrol valve mechanism as previously described.

In addition to the aforesaid possibilities of accumulating unburned gasin an oven, there-is one other condition under which unburned gas couldcollect in an oven. Our improved control apparatus is also designed totake care of thiscontingency and prevent the accumulation of unburnedgas in an oven should this condition ever occur. For example, assumethat while the main burner is operating normally the main control valveis closed and then immediately opened again before the thermocouple andthe thermostatic element have had time to cool. The closing of the maincontrol valve extinguishes both the main burner and the pilot burner bycutting off the supply of gas thereto. Then when the main control valveis immediately reopened gas is again supplied to both the main burnerand the pilot burner since the thermocouple has not had time to coolsufiiciently to allow the safety control valve mechanism to operate tocut oif the supply of gas to both burners. But under this condition thepilot burner will not be ignited because the still hot thermostaticelement is maintaining the normally closed switch open and preventingenergization of the electric ignition element and of the soleniod. Thusunburned gas will escape from both the main burner and the pilot burnerinto the oven until the thermostatic element cools and closes thenormally closed switch. As soon as the thermostatic element coolssufiiciently it will energize the ignition'element which will ignite thepilot burner and it in turn will ignite the main burner. But in themeantime enough gas may have escaped into the oven from the main burnerand the pilot burner to cause a bad explosion when the pilot burner isagain ignited. In order to eliminate the escape of any unburned gas intothe oven whenever-this condition occurs, I provide an interrupter switchin the circuit between the thermocouple and the safety control valvemechanism. This switch is located in the same casing as the mastercontrol switch and is opened and closed by the closing and opening ofthe main control valve simultaneously with the opening and closing ofthe master control switch. Then when the main control valve. is closedto cut off the supply of gas to the burner the interrupter switch issimultaneously opened, breaking the circuit between the thermocouple andthe safety control mechanism which permits the safety control switchmechanism to cut oil all communication to both the pilot burner and themain burner. Then when the main control valve is immediately openedafter having been momentarily closed nothing will happen until thethermostatic element cools and closes the normally closed switch whichoccurs between six and ten seconds. After that the apparatus functionsin its normal manner as has been explained. 1

When it is desired to use the apparatus in conjunction with any standardtime control mechanism we provide a supplemental master switch and asupplemental interrupter switch which ar'e'simultaneously opened andclosed at predetermined times by the time control mechanism. Thesupplemental master switch is inserted in the main circuit iniserieswith the pri- 'mary master switch, and the supplemental interrupterswitch is inserted ,-in the thermocouple circuit inseries. with theprimary interrupter switch. In use the time control. mechanism is nismthe apparatus will function in the same manner as previously described.When a range is equipped with a time control mechanism, means to lockthesupplemental switches closed is also provided in order that theapparatus may be used independently of the time control mechanism ifdesired.

Theprincipal object of the invention is to provide an improvedelectrical ignition and automatic control system for cooking range ovenburners using gaseous fuel.

Another object of the invention is to provide in an electrical ignitionand control system of the character described improved means forcompletely shutting off the supply of gas to both the main burner andthe pilot burner in the event the pilot burner becomes extinguished forany reason before the supply of gas to both the main burner anld thepilot burner is cut off by the main control va ve.

Another object of the invention is to provide in an apparatus of thecharacter described means to prevent the escape ofany unburned gas inthe event the main contr'olvalve is turned off after a period ofoperation and is then immediately turned back. on-before the heatresponsive elemerlits inthe system-have had an'opportunity to coo aStill another object of theinvention is to provide an improvedelectricalignition and control system of the character described whichmay be used conjunction with a time control mechanism or independentlythereof as desired.

Other and more limited objects of the invention will be apparent fromthe following specification and the accompanying drawing forming a partthereof, wherein:

Fig. l is a diagrammatic view illustrating our improved electricalignition and safety control mechanism as applied to a cooking range ovenburner using gaseous fuel;

tical section throughthe safety control valve mechanism showing thevarious parts in the position they assume when-the oven burner is Fig.3' is a view similar to Fig. 2 showing the various parts in thepositions they are automatically moved to when the main control valve isfirst turned on to initiate the operation of the main oven burnerr vFig. 4 is a horizontal section taken on the line 44'of F18. 1;

Fig. is a wiring diagramof'the apparatus as used independently of a timecontrol mechanism; and y Fig. 6 is a wiring diagram of the apparatus asused in conjunction with a time control mech- Referring now to thedrawings by reference characters, the numeral I indicates a gaseous fuelburner which is mounted in or in heating relation to a cooking rangeoven 2. Gaseous fuel is supplied to the burner I from a manifold (notshown) through a conduit 3. Interposed in the conduit 3 are a maincontrol valve 4, a safety control valve mechanism generally indicated bythe numeral 6, and an oven temperature control valve 6. The main controlvalve 4 is a cut off valve of standard construction which when in openor on position permits the flow of gas through the conduit 3 from themanifold to the burner I, and in closed or off position cuts oil flow ofgas to the burner I. This valve is manually opened and closed by ahandle I and a valve stem 8, and directly controls the operation of theentire apparatus in that it initiates the operation of the entireapparatus when it is turned to the on position and terminates theoperation when it is turnedto the ofi position. From the main controlvalve 4 gas flows through a connector 3 to the safety control valvemechanism 5, to be described in detail hereinafter. From the safetycontrol valve mechanism 5 the gas flows through a connector III, theoven temperature control valve 6 and the conduit 3 to the burner I. Theoven temperature control valve 6 is operative to regulate the amount ofgas flowing to the bumer I in order to maintain the oven at any desiredset temperature. The valve 6 is set to any desired temperature by ahandle II having a pointer I2 which cooperates with a graduated dial I3carried by the valve 6. The valve 6 is controlled according to thetemperature setting by a thermostatic element I4 which is mounted in the"oven 2 and is connected to the valve 6 as shown quently it is not shownin detail herein. Thereare many different constructions available anyone of which will work equally well herein. Gas is also supplied to apilot burner I6 through a branch conduit I! which extends between thesafety control valve mechanism and the pilot burner I6. The pilot burnerI6 is disposed adjacent the rear end of the main burner I in position toignite the burner I when gas is supplied thereto. An electrical ignitionelement I3 is operatively associated with the pilot burner I6 inposition to ignite the pilot burner I6 when gas is supplied thereto. Athermostatic element I8 and a thermocouple 26 .are mounted in positionto be heated by a flame from the pilot burner. The thermostatic elementI3 is operative to open and close a switch 2| which controls theenergization of the electrical ignition element I8 severed ends.

and a solenoid 22 which when energized operates the safety control valvemechanism to 'sup-' ply gas to the pilot burner I6 as will be -describedin connection with the description of the safety control valve mechanismand the operation of thewhole apparatus. The thermocouple 26 when heatedis operative to holdthe safety control valve mechanism in condition tomaintain the supply of gas to both the pilot burner I6 and the mainburner I, as will also be described in connection with the descriptionof the safety controlvalve mechanism and the operation of the apparatus.A switch mechanism 23 which is associated with the main controlvalve 4is adapted to be opened and closed simultaneously with the closing andopening of the main control valve 4.' As the control valve 4 is turnedfrom the off or closed position to the on or opened position the switchmechanism 23 is moved from the open position to the closed position byan operating lever 24 which 'cooperates with a cam section 25 on themain control valve stem 3. Conversely, when the main control valve 4 isturned from the open or on position to the closed or oil position theswitch mechanism 23 is moved from the closed position to the openposition.

An electric circuit between the thermocouple 26 and the safety controlvalve mechanism 5 is established by a copper tube 26 which encloses aninsulated wire 21. The wire 21 is severed between the thermocouple 20and the safety control mechanism 5 and an interrupter 26 havingterminals 29 and 30 is interposed between the One of the severed ends ofthe wire 21 is connected to the terminal 23 and the other severed end isconnected to the terminal 30. The purpose and function of theinterrupter 28 will be explained in detail in connection with thedescription of the operation of the apparatus.

The construction of the safety control valve mechanism 5 and itsconnection to the solenoid 22 will now be described, reference being hadto Figs. 2, 3 and 4 of the drawing. This mechanism comprises a casing 35having a chamber 36 in one end thereof and a chamber 31 in the other endthereof. The chambers 36 and 31 are connected by a bore 33 of reduceddiameter. A valve seat 33 is located at one end of the bore 33 and asimilar valve seat 40 is located at the other end of the bore 36. Thechamber 36 is closed by a removable cap H and the chamber 31 is closedby a removable cap 42. A sleeve 43, having end walls 44 and 46, iscarried by the cap 4I and extends into the chamber 36. A valve stem 46which is slidably mounted in a bushing 41 carried by theend wall 46 ofthe sleeve 43, extends from the chamber 36 into the sleeve 43. A valvedisc 48 of suitable material is secured to one end of the valve stem 46within the chamber 36, and a metal disc 43 is secured to'the other endof the stem 46 withinthe sleeve 43. A spring 60 disposed about the valvestem 46 between the valve disc 43 and the end wall 46 of the sleeve 43normally holds the valve disc 48 against the valve seat 33. A horseshoemagnet BI is secured to one end of a hollow exteriorly threaded stud 62which extends out through aligned apertures in the end wall 44, of thesleeve 43, and in the end of the cap M. A nut 53 screwed onto the outerportion of the stud 62 securely holds the magnet BI and the sleeve 43 inplace. The legs of the magnet 6i have a winding 54 thereon one end ofwhich is connected to the tube 26 and the other end of which isconnected to the wire 2'! in the tube 29. The tube 26 is inserted intothe hollow stud 32 and is held in place by a screw fitting 62a. A sleeve66 is screwed into a threaded recess in the end of the cap 42, asindicated at 66, and extends into the chamber 31 a slight distance. Oneend of the sleeve 66 is closed by an end wall 61, and the other endwhich is open registers with a circular aperture 68 in the end wall ofthe cap 42. A plug 69 is slidably mounted in the sleeve 66 and extendsout through the aperture 69 in the cap 42. The outer end of the plug 69has a reduced extension 48 formed integral therewith, providing anannular shoulder 6I around the extension 69 at the outer end of the plug69. A stem 62 which is secured to the inner end of the plug 69 extendsout through an aperture 63, in the end wall 61 of the sleeve 66, andthrough the chamber 31 and into the bore 38. The stem 62 has a collar 64rigidly secured thereon between the end wall 61 and the outer end of thestem. A valve disc 66 of suitable material is slidably mounted upon thestem 62 between the end wall 61 of the sleeve 65 and the collar 64. Thevalve disc 65 is adapted to engage the valve seat 48 to cut oil the flowof gas into the chamber 31 during the initiation of operation as will behereinafter described. A compression spring 66 disposed about the stem62 between the end wall 61 and the valve disc 66 normally yieldinglyholds the valve disc 66 against the collar 64. A compression spring 61which is stronger than the spring 66 is disposed about the stem 62within the sleeve 66 between the inner face of the end wall 61 and theinner end of the plug 59. The spring 61 is operative to return the plug59, stem 62 and valve disc 66 from the position shown in Fig. 3 back totheir normal position as shown in Fig. 2, against the resistance of thespring 66. A port 68 in the casing 36 provides communication between thechamber. 36 and the connector 9 to allow gas to flow from the 'maincontrol valve 4 through the connector 9 and into the chamber 36. Duringnormal operation of the main burner I gas flows from the chamber 36through the reduced intermediate bore 38 and into the chamber 31. A port69 which establishes communicationbetween the conduit I1 and the bore 38is provided to supply gas to the pilot burner I6; and a port 18establishes communication between the chamber 31 and the connector I8 topermit the flow of gas from the chamber 31 to the main burner I throughthe oven temperature control valve and the conduit 3.

The safety control valve mechanism 5 is operatively connected to thesolenoid 22 by a yoke 12 and a link 13. The yoke 12 which encompassesthe safety control valve mechanism 5 as shown in Fig. 4 comprises a pairof spaced parallel arms 14 which are connected together at one end by abridge 15. The bridge 15 has an aperture 16 therein through which thereduced end 68 of-- the plug 59 extends with the inner face of thebridge engaging the shoulder 6I between the plug 59 and the reducedei'rtension 68 thereof. The other ends of the arms 14 terminate in apair of spaced parallel ears 11 to and between which one end of the link13 is pivotally connected. The other end of the link 13 is pivotallyconnected to the movable core 18 of the solenoid 22 as indicated at 19.

The switch mechanism 23 consists of the master control switch 88 and theinterrupter switch 8|. The master control switch 88 comprises thecontacts 82 and 83 which are adapted to be bridged by the conductor bar84; and the interrupter switch 8| comprises the contacts 96 and 86 whichare adapted to be bridged by the conductor bar 81. The switch 2Icomprises three contacts 88, 89 and 98 which are adapted to be bridgedby a conductor bar 9] when the switch is in its normal closed position.

The supplemental master switch which is shown at 92 in Fig. 6 comprisesthe contacts 93 and 94 which are adapted to be bridged by a conductorbar 95; and the supplemental interrupter switch which is shown at" inFig. 6 comprises the contacts 91 and 98 which are adapted to be bridgedby a conductor bar 99. The conductor bars 95 and 99 are mounted on abase I88, of insulating material, which is adapted to be moved towardand away from the contacts 93, 94, 91 and 98 at predetermined times by atime control mechanism I8I through a connecting link I82. When it isdesired to operate the oven burner of a range which is equipped with atime control independently of the time control mechanism, the switches92 and 96 are locked in closed position through the medium of a manuallyoperable button I83 incorporated in the time control mechanism IN.

The operation of the apparatus will now be described in connection withFig. 5 which is a wiring diagram showing the electrical circuits of ourimproved ignition and control apparatus without a time control mechanismincorporated therein.v To initiate the operation of the oven burner I itis only necessary to set the oven temperature control valve 6 to thedesired temperature and to manually turn the main control valve 4 fromthe off position to the on position. After that the ignition andoperation of the burner are automatically controlled until the operationof the-burner is terminated by manual y turning the main control valve 4from the on position to the off position. As the main control valve 4 isturned from the off position to the on position the master switch 88 andthe interrupter switch 8I are simultaneously closed by the cam 25 andlever 24. After the main control valve has been opened gas can flow fromthe manifold through the main control valve 4 and into the chamber 36 ofthe safety control valve mechanism 5, the various parts of which are inthe position shown in Fig. 2. But the gas can go no farther since thevalve disc 48 is being held against the valve seat 39 by the spring 58,thus closing the only exit from the chamber 36. As soon as the switch 88is closed current flows from one side I of the line through the lead I86to the terminal 82 and thence through the conductor bar 84 to theterminal 83. From the terminal 83 the current flows through the lead I81to the terminal 88 of the normally closed switch 2|, and thence throughthe conductor bar 9| to the terminals 89 and 98. From the terminal 89the current flows through the leadv I88 to the electrical resistanceignition element I8, thence through the ignition element I8 and back tothe other side I89 of the line through the lead II8, thus completing acircuit through the ignition element I8 which energizes it and rendersit operable to ignite the pilot burner I6 as soon as gas is suppliedthereto. From the terminal 98 of the normally closed switch 2I thecurrent also flows through the lead III to the solenoid 22, thencethrough the winding of the solenoid and back to the other side J89 ofthe line through the lead I I2, thus completing a circuit whichenergizes the solenoid 22. ,The energization of the solenoid 22 causesit, through the link 13 and yoke 12, to

' 9 shift the various parts of the safety control valve mechanism fromthe position shown in Fig. 2 to the position shown in Fig. 3. In thisposition the valve disc 43 is held away from the valve seat 39 and themetal disc 49 is held against the ends of the legs of the magnet 6| bystem 62 acting against the resistance of the spring 56. This allows gasto flow from the chamber 36 into the bore 38 and thence through the port69 and conduit l1 to the pilot burner l6 where it is ignited by theignition element I8. But the gas cannot yet flow to the main burner Isince the valve disc 65 is being held against the seat 46 by the spring66 which cuts oiT communication between the bore 33 and the chamber 31.As soon as the pilot burner I6 is ignited it projects a flame againstand heats both the thermocouple .29 and the thermostatic element l3. Theheating of the thermocouple 20 generates a minute current whichenergizes the magnet suiflciently for it to hold the metal disc 49 andthe stem 46 and valve disc 48 secured thereto in the position shown inFig. 3 against the pressure of the spring 50 after the disc 49 has beenmoved into engagement withthe magnet 5i by the solenoid 22.v But themagnet 5i when energized by the thermocouple 26 is not strong enough toattract and withdraw the metal disc 49, and the stem 46 and valve disc46 secured thereto, from the position shown in Fig. 2 to the positionshown in Fig. 3. It can only hold these parts in this position afterthey have-been moved thereto by the solenoid 22 through the medium ofthe link 13, yoke 12, plunger 59 and stem 62. The electric circuitbetween the thermocouple 26 and the winding 54 of the magnet 5| isthrough the copper tube 26, which extends unbroken between thethermocouple and the winding 54, and the wire 21 which is severedbetween the winding 54 and the thermocouple 29. One of the severed endsof the wire 21 is connected to the terminal 54. From the winding thecurrent will flow back through the wire 21 to the terminal 29.

From the terminal 29 the current will flow through lead. II5 toandthrough the switch 3i,

and back to the terminal 30 through the lead I I 6. From the terminal 36the current will flow back to the thermocouple 26 through the othersection of the wire 21, completing the circuit between the thermocouple20 and the winding 54 of the magnet 5|. This circuit will be maintainedas long as the thermocouple is heated. After the thermostatic element I9has been heated sufliciently, which is after the thermocouple hasenergized the magnet 5i, it will open the norma ly closed switch 2i,breaking the circuit to and de-energizing both the ignition element I6and the solenoid 22. After the pilot burner has been ignited there is nofurther need to main- ,tainthe ignition element energized. As soon asthe solenoid ,22 is de-energized the spring 61 will return the plunger59, stem 62 and valve disc 65 back from the position shown in Fig. 3 tothe position shown in Fig. 2 against the pressure of the spring 66., Thevalve disc 43 will be held in the position'shown in Fig. 3 by the magnet5|.

Communication is then established between the chambers 36 and 31 throughthe bore 36. Gas will then flow from the chamber 36 into the chamber 31through the bore 36. From the chamber 31 gas will flow through the oventemperature control valve '6 and conduit 3 to the main burner I where itwill be ignited by the pilot burner I6. The apparatus is now operatingnormally, and in the absence of any abnormal conditions it will continueto do so, provided the pilot burner remains ignited, until the supply ofgas to both the pilot burner and the main burner is cut off by themanual closing of the main control-valve 4.

In the event the pilot burner I6 is extinguished for any reason duringoperation, the thermocouple 20 will cool in a few seconds andde-energize the magnet 5|. magnet 5| will allow the spring 59 to movethe valve disc 48 back into engagement with the valve seat 39, as shownin Fig. 2, which will cut of! the flow of gas from the chamber 36 intothe bore 33 and chamber 31, and from them to the pilot light I6 and themain burner. l. The burner I will then be extinguished along with thepilot burner. As soon as the thermostatic element I9 cools it willclosethe switch 2| which will energizeboth the ignition element I3 and thesolenoid 22 as previously described since the main control valve 4 isstill open and the switches and 8i are closed. The pilot burner I6 willthen be reignited and the rest of the apparatus will again function asdescribed, provided there is gas available. If no gas is availableeverything will remain in condition to ignite the pilot burner andre-initiate operation as 'soon as gas is again available. In the eventof either a momentary or prolonged power failure during operation, theapparatus will continue to operate normally until terminated by themanual closing of the main control valve, provided of course that allother conditions are normal. In order to operate the apparatus during aprolonged power failure which occurred prior to operation, it is onlynecessary to hold a match to the pilot burner I6 and manually move theplunger 59 from the position shown in Fig. 2 to the positionshown inFig. 3 and hold it in this position a suflicient time for thethermocouple 26 to become heated, after which the plunger 59 may bereleased and allowed to be returned to its initial position by thespring 61. The apparatus will then continue to function normally asdescribed under the control of the pilot burner I6 and the oventemperature control valve 6. When the time control mechanism IOI isincorporated in the apparatus as shown in Fig. 6, we interpose -thesupplemental master switch 92 in the lead I01,.between the contact 83 ofthe master switch 99 and the contact 86 of the normally closedthermostatically operated switch 2|, in series with the master switch60; and we interpose the supplemental interrupter switch 96 in the leadH6, between the contact 91 of the interrupter switch 96 and the terminal30 of the interrupter 28, in series with the interrupter switch 9'6. Thetime control mechanism when used is operative to close the switches 92and 96 at a predetermined set time and to open the switches at apredetermined' set later time. After the switches 32 and 96 have beenclosed the mechanism functions in exactly the same manner as describedin connection with Fig. 5, until at the predetermined set later time thetime control mechanism opens theswtiches 92 and 9,6 which terminates Thede-energizing oi' the the operation just as effectivelyas if the maincontrol valve had been turned off. The opening of the supplementalmaster switch 82 by the time control mechanism at the predeterminedlater time has no effect upon the operation of the apparatus; but theopening of the supplemental interrupter switch 98 breaksthe circuitbetween the thermocouple 20 and the safety control valve mechanism whichde-energizes the magnet and allows the spring to move the valve disc 48from the position shown in Fig. 3

into engagement with the valve seat 39 as shown in Fig. 2. This closesthe exit from the chamber 36 and completely cuts offthe 'supply-ofgas toboth the main bumer land'the pilot burner l8.- The main control valve4'can then be-manually.

event the pilot burner is extinguished for am! 7 herein as variousmodifications may be made "therein within-the scope of the appendedclaims.

closed at any time after the timecontr'ol mechanism has terminatedoperation. Operation cannot again be initiated until; the fmainfcontrol" valve 4 is opened and '96 are closed; 2

As previously statedpit mitea'lyjhisatstthat afterthe apparatus has,-been in op ration for.

the switches ill, 8],, and

sometime the operator turns the main control valve off and then immediately turns it on again before the thermocohplelll and theythermostatic element have had 'ajn opportunity to=cool The closing ofthe maincont'rol.valvel cuts off th e i, supply of gas to andextinguishes'iboththe main burner l and the? pilot burner it. .*..Underthis 'condition, if the interrupter switch fflfwas not interposed in thecircuit between the thermocouple 20 andthe safety.control valvemechanism 5 and arrangedto be opened and closed by the closing andopening of the main control valve 4, unburned gas would escape into theoven from both the pilot burner and the main burner until thethermocouple cooled and cut off the supply of gasto' both burners aspreviously described. During this time sufficient gas could accumulatein the oven to cause abad explosion when the pilot burner or the mainburner l What is claimed is:

' -1-. In an automatic ignition and control anparatus of the characterdescribed, the combination of a" main burner,. a pilot burner operative"to" ignite said 'main burner, a conduit through whichgaseous fuel "issupplied to said main burner; a; manually operable main control valve byfwhich 'the supply of fuel to said main burner and said pilot burner isprimarily controlled, a

safety controlvalve mechanism interposed in said conduit between saidmain control valve and said "-m'ain burner, a secondary conduitextending between said safety control valve mechanism and q said pilotburner through which gaseous fuel is supplied to said pilot burner, saidsafety control valve mechanism. being operative to control the supply offuel to said main burner and said pilot burner after the fuel leavessaid main control valve, a solenoid operatively connected to said safetycontrol valve mechanism, said solenoid being operative upon.energization to set said safety control valve mechanism in condition tosupply fuel to said pilot burner while cutting off the supply of fuel tosaid main burner and upon subsequent de-energizationto set said safetycontrol valve mechanism in condition to also supply fuel to said mainburner, a normally closed switch operative to control the energizationof said sole- I noid, and a thermostatic element adapted to be wereagain ignited; Therefore" we provide the interrupter switch 8| in order:to preventany escape of unburned gas when thiscondition occurs.

With the interrupter switch 8i arranged as shown a and described themomentary closing of the main heated by said pilot burner and operativeto maintain said switch open when heated and closed when cool."

2. In anautomatic ignition and control apparatus of the characterdescribed, the combinacontrol valve 4 will simultaneously operrtheinterrupter switch 8|. The opening of the interrupter switch ill willbreak the circuit between the thermocouple and the safety control valvemechanism and de-energize the magnet 5| even though the thermocouple isstill hot. The deenergization of the magnet 51 allows the spring to movethe valve disc 48 into position to cut off the supply of gas to both themain burner and the pilot burner "as previously described.

The immediate .opening of the control valve 4 under this condition willhave no effect upon the apparatus until the thermostatic element l9cools and closes the switch 2|. This is due to the fact that themagnetil when energized is not strong enough to shift the valve disc48;'andthe connected *parts from the closed position shown in Fig. 2 tothe open position showri-ginlFigB,

but can only hold them in this-position; after they have'been movedthereby the solenoid Z2."' Afte r the thermostatic element I9 cools andcloses the switch 2|, which takes from six to ten seconds;

tion of a main .burner,- a pilot burner operative to ignite said mainburner, a conduit through which gaseous fuel is supplied to said mainburner, a manually. operable main control valve by whichvthe supply offuelto said main burner and said pilot burner is primarily controlled, asafety control-valve mechanism interposed in said conduit between saidmain control valve and said main burner, a secondary conduit extendingbetween said safety control valve mechanism and said pilot burnerthrough which gaseous fuel is supplied to said pilot burner, said safetycontrol valve mechanism being operative to control the supply of fuel tosaid main burner and said pilot burner after the fuel leavessaid maincontrol valve, a solenoid operatively connected to said safety controlvalve mechanism, said solenoid being operative upon energization' to setsaid safety control valve mechanism in condition to 1 supply fuel tosaid pilot burner while cutting off the supply of fuel to said mainburner and upon the ignition element l8 and the solenoid are againenergized after which the operationipro'-'-' ceeds as previouslydescribed. v I r Operating current is supplied tothe'time controlmechanism llil from the line l05i+l09bythe leads H1 and H8.

From the foregoing it will be seen that in the subsequentde-energization to set said safety control valve mechanism in conditionto also supply fuel to said m'ain burner, a normally open masterswitchwhich is operative when closed to energize said solenoid,-anormally closed switch which is operative-when opened to de-energizesaid solenoid, and a thermostatic element adapted to be heated by saidpilot burner and-op erative when heated to maintain said normally closedswitch open and when coolto maintain said normally closed switch closed.v

3. In an automatic ignition and control apparatus of the characterdescribed, the combination of a main burner, a pilot burner operative toignite said main burner, an electric ignition element operative whenenergized to ignite said pilot burner, a conduit through which gaseousfuel is supplied to said main burner, a manually operable main controlvalve. by which the supply of fuel to said main burner and said pilotburner is primarily controlled, a, safety control valve mechanisminterposed in said conduit between said main control valve and said mainburner, a secondary conduit extending between said safety control valvemechanism and said pilot burner through which gaseous fuel is suppliedto said pilot burner. said safety control valve mechanism beingoperative to control the supply of fuel to said main burner and saidpilot burner after the fuel leaves said main control valve, a solenoidoperatively connected to said safety control valve mechanism, saidsolenoid being operative upon energization to set said safety controlvalve mechanism in condition to supply fuel to said pilot burner whilecutting oil the supply of fuel to said main burner and upon subsequentde-energization to set said safety control valve mechanism in conditionto also supply fuel to said main burner, a normally open master switchassociated with said main control valve, operative connections betweensaid main control valve and said master switch through which said masterswitch is closed by the opening of said main control valve and is openedby the closing of said main control valve, said master switch beingoperative when closed to energize said solenoid and said electricignition element, a normally closed switch disposed in series with saidmaster switch which is operative when opened to deenergize said solenoidand said electric ignition element, a thermostatic element adapted to beheated by said pilot burner and operative when heated to maintain saidnormally closed switch open and when cool to maintain said normallyclosed switch closed.

4. In an automatic ignition and control apparatus of the characterdescribed, the combination of a main burner, a pilot burner operative toignite said main burner, a conduit through which gaseous fuel issupplied to said main burner. a manually operable main control valve bywhich the supply of fuel to said main burner through which gaseous fuelis supplied to said pilot burner, said safety control valve mechan smincluding a normally open valve and a normally closed valve, a solenoidoperatively connected to said safety control valve mechanism, saidsolenoid being operative upon energization to close said normally openvalve andto open said normally closed valve and upon subsequent (18-811?ergization to reopen said normally open valve,-a

thermocouple adapted to be heated by said pilot burner and operativewhen heated to maintain said normally closed valve open after it hasbeen opened by the action of said solenoid whereby fuel is firstsupplied to said pilot burner and then upon the subsequentde-energization of said solenoid fuel is supplied to both said pilotburner and said main burner, a normally open master switch which isoperative when closed to energize said solenoid, a normally closedswitch which is operative when opened to de-energize said solenoid, anda thermostatic element adapted to be heated by said pilot burner andoperative when heated to maintain said normally closed switch open andwhen cool to maintain said normally closed switch closed.

5. In an automatic ignition and control apparatus of the characterdescribed, the combination of a main burner, a pilot burner operative toignite said main burner, an electric ignition element operative whenenergized to ignite said pilot burner, a conduit through which gaseousfuel is supplied to said main burner, a manually operable main controlby which the supply of fuel to said main burner and said pilot burner isprimarily controlled, a safety control valve mechanism interposed insaid conduit between said main control valve and said main burner andoperative to control the supply of fuel'to said main burner and saidpilot burner after the fuel leaves said main control valve, a secondaryconduit extending between said safety control valve mechanism and saidpilot burner through which gaseous fuel is supplied to said pilotburner, said' safety control valve mechanism including a normallyopenvalve and a normally closed valve, a solenoid operatively connectedto said safety control valve mechanism, said solenoid being operativeupon energization to close said normally open valve and to open saidnormally closed valve and upon subsequent de-energization to reopensequent de-energization of said solenoid fuel is supplied to both saidpilot burner and said main burner, a normally open master switchassoci-.-.

ated withsaid main control valve, operative connections between saidmain control valve and said master switch through which said masterswitch is closed by the opening of said main control valve and is openedby the closing of said main control valve, said master switch beingoperative when closed to energize said solenoid and said electricignition element, a normally closed switch disposed in series with saidmaster switch which is operative when opened to de-energize saidsolenoid and said electric ignition element, a thermostatic elementadapted-to be heated by said pilot burner and operative when heated tomaintain said normally closed switch open and when cool to maintain saidnormally closed switch closed.

6. In an automatic ignition and control apparatus of the characterdescribed, the combination of a main burner, a pilot burner operative toignite said main burner, a conduit through which gaseous fuel issupplied to said main burner, a manually operable main control valve bywhich the supply of fuel to said main burner and said pilot burner isprimarily controlled, a safety control valve mechanism interposed insaid conduit between said main control valve and said main burner, asecondary conduit extending between said safety con m chanism and saidpilot burner through which gaseous fuel is supplied to said pilotburner, said safety control valve mechanism being operative to controlthe supply of fuel to said main burner and said pilot burner after the.fuel leaves said main control valve. a

solenoid operatively connected to said safety control valve mechanism,said solenoid being operative upon energization to set said safetycontrol valve mechanism in condition to supply fuel to said pilot burnerwhile cutting off the supply of fuel to said main burner and uponsubsequent de-energization to set said safety control valve mechanism incondition to also supply fuel to said main burner, an electromagnetassociated with said safety control valve mechanism and operative whenenergized to maintain said safety control valve mechanism in said setcondition, a thermocouple adapted to be heated by said pilot burner, anelectric circuit between said thermocouple and said electromagnetthrough which said magnet is energized by said thermocouple when heated,an interrupter switch interposed in said circuit and operative to openand close said circuit and thereby control the energization of saidelectromagnet, a normally open master switch which is operative whenclosed to energize said solenoid, a normally closed switch which isoperative when opened to de-ener ize said solenoid, and a thermostaticelement adapted to be heated by said pilot burner and operative whenheated to maintain said normally closed switch open and when cool tomaintain said normally closed switch closed.

7. In an automatic ignition and control apparatus of the characterdescribed, the combination of a main burner, a pilot burner operative toignite said main burner, an electric ignition element operative whenenergized to ignite said pilot burner, a conduit through which gaseousfuel is supplied to said main burner, a manually operable main controlvalve by which the supply of fuel to said main burner and said pilotburner is primarily controlled, a safety control valve mechanisminterposed in said conduit between said main control valve and said mainburner, a secondary conduit extending between said safety control valvemechanism and said pilot burner through which gaseous fuel is suppliedto said pilot burner, said safety control valve mechanism beingoperative to control the supply of fuel to said main burner and saidpilot burner after the fuel leaves said main control valve, a solenoidoperatively connected to said safety control valve mechanism, saidsolenoid being op rative upon energization to set said safety controlvalve mechanism in condition to supply fuel to said pilot burner whilecutting off the supply of fuel to said main burner and upon subsequentde-energization to set said safety control valve mechanism in conditionto also supply fuel to said main burner, an electromagnet associatedwith said safety control valve mechanism and operative when energized tomaintain said safety control valve mechanism in said set condition, athermocouple adapted to be heated by said pilot burner, an electriccircuit between said thermocouple and said electromagnet through which.

said electromagnet is energized by said thermocouple when heated, aninterrupter switch interposed in said circuit and operative to open andclose said circuit and thereby control the energization of saidelectromagnet, a normally open master switch associated with said maincontrol valve, operative connections between said main control valve andsaid master switch through which said master switch is closed by theopening of said main control valve and is opened by the closing of saidmain control valve, said master switch being operativewhen closed toenergize said solenoid and said electric ignition element, a normallyclosed switch disposed in series with said master switch which isoperative when opened to de-energize said solenoid and said electricignition element, a thermostatic element adapted to be heated by saidpilot burner and operative when heated to maintain said normally closedswitch open and when cool to maintain said normally closed switchclosed.

8. In an automatic ignition and control apparatus of the.characterdescribed, the combination of a main burner, a pilot burner operative toignite said main burner, a conduit through which gaseous fuel issupplied to said main burner, a manually operable main control valve bywhich the supply of fuel to said main burner is primarily controlled, asafety control valve mechanism interposed in said conduit, a secondaryconduit extending between said safety control valve mechanism and saidpilot burner through which gaseous fuel is supplied to said pilotburner, said safety control valve mechanism being operative to controlthe supply of fuel to said main burner after said main control valve hasbeen opened, means through which said safety control valve mechanism isset in condition to supply fuel to said pilot burner and said mainburner, an electromagnet associated with said safety control valvemechanism and operative when energized to maintain said safety controlvalve mechanism in said set condition, a thermocouple adapted to beheated by said pilot burner, an electric circuit between saidthermocouple and said electromagnet through which said electromagnet isenergized by said thermocouple when heated, an interrupter switchinterposed in said circuit and operative to open and close said circuitand thereby control the energization of said electromagnet, saidinterrupter switch being associated with said main control valve, andoperative connections between said main control valve and saidinterrupter switch through which said interrupter switch is closed bythe opening of said main control valve and is opened by the closing ofsaid main control valve.

9. In an automatic ignition and control apparatus of the characterdescribed, the combination of a main burner, a pilot burner operative toignite said main burner, a conduit through which gaseous fuel issupplied to said main burner, a manually operable main control valve bywhich the supply of fuel to said main burner and said pilot burner isprimarily controlled, a safety control valve mechanism interposed insaid conduit between said main control valve and said main burner andoperative to control the supply of fuel to said main burner and saidpilot burner after the fuel leaves said main control valve, a secondaryconduit extending between said safety control valve mechanism and saidpilot burner through which gaseous fuel is supplied to said pilotburner, said safety control valve mechanism including a normally openvalve and a normally closed valve, a solenoid operatively connected tosaid safety control valve mechanism, said solenoid being operative uponenergization to close said normally open valve and to open said normallyclosed valve and upon subsequent deenergization to reopen said normallyopen valve. an electromagnet associated with said safety control valvemechanism and operative when energized to hold said normally closedvalve open after it has been opened by the action of said couple andsaid electromagnet through which said electromagnet is energized by saidthermocouple when heated, an interrupter switch interposed in saidcircuit and operative to open and close said circuit and thereby controlthe energization of said electromagnet, said interrupter switch beingassociated with said main control valve, and operative connectionsbetween said main control valve and said interrupter switch throughwhich said interrupter switch is closed by the opening of said maincontrol valve and is opened by the closing of said main control valve.

10. In an automatic ignition and control apparatus of the characterdescribed, the combination of a main burner, a pilot burner operative toignite said main burner, a conduit through which gaseous fuel issupplied to said main burner, a manually operable main control valve bywhich the supply of fuel to said main burner is primarily controlled, asafety control valve mechanism interposed in said conduit, a, secondaryconduit extending between said safety control valve mechanism and saidpilot burner through which gaseous fuel is supplied to said pilotburner, said s fety control valve mechanism being operative :2 controlthe supply of fuel to said main burner ter said main control valve hasbeen opened, means through which said safety control valve mechanism isset in condition to supply fuel to said pilot burner and said mainburner, an electromagnet associated with saidsafety control valvemechanism and operative when--:energized to maintain said safety controlvalve mechanism in said set condition, a thermocouple adaptedto beheated by said pilot burner, an electric circuit between saidthermocouple and said electromag,

net through which said magnet is energized by' said thermocouple whenheated, an interrupter switch interposed in said circuit and operativeto open and close said circuit and thereby control the energization ofsaid electromagnet, operative connections between said main controlvalve and said interrupter switch through which said interrupter switchis closedby the opening of said main control valve and is opened by theclosing of said main control valve, a supplemental interrupter switchinterposed in said circuit in series with said interrupter switch, and atime control mechanism operative to close and open said supplementalinterrupter switch at predetermined mechanism interposed in said conduitbetween said main control valve and said main burner, a secondaryconduit extending between said safety control valve mechanism and saidpilot burner through which gaseous fuel is supplied to said pilotburner, said safety control valve 18 v mechanismbeing operative tocontrol the supply of fuel to said main burner and said pilot burnerafter the fuel leaves said main control valve, a solenoid operativelyconnected to said safety con- 5 trol valve mechanism, said' solenoidbeing operative upon energization to set said safety control valvemechanism in condition to supply fuel to said pilot burner while cuttingoff the supply of de-energization to set said safety control valvemechanism in condition to also supply fuel to said main burner, anelectromagnet associated with said safety control valve mechanism andoperative when energized to maintain said safety control valve in saidset condition, a thermocouple adapted to be heated bysaid pilot burner,an electric circuit between said thermocouple and said electromagnetthrough which said magnet is energized by said thermocouple when saidthermocouple is heated, an interrupter switch interposed in said circuitand operative to make and break the circuit between said thermocoupleand said electromagnet and thereby control the energization of saidelectromagnet, operative connections between said main control valve andsaid interrupter switch through which said interrupter switch is closedand opened by the opening and closing of the main control valve, a nor--mally open master switch associated with said main control valve,operative connections between said main control valve and said masterswitch through which said master switch is closed by the opening of saidmain control valve and is opened by the closing of said main controlvalve,

said master switch being operative when closed to energize said solenoidand said electric ignition element, a normally closed switch disposed inseries with said master switch which is operative when opened tode-energize said solenoid and said electric ignition element, athermostatic element'adapted to be heated by said pilot burner andoperative when heated to maintain said normally closed switch open andwhen cool to maintain said normally closed switch closed, a supplementalmaster switch disposed in series with said master switch and saidnormally closed switch, a

*supplemental interrupter switch interposed in said circuit in serieswith said interrupter switch, and a time control mechanism operative tosimultaneously close and open said supplemental master siyitch and saidsupplemental interrupter switch at predetermined set times.

CHARLES M. MAYER. JOHN M. HOFF.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name 7 Date 1,174,442 Phillips Mar. 17,1916 1,178,272 Simke Apr. 4, 1916 2,249,442 'Thornbery July 15, 1941 52,276,909 Alfery Mar. 17, 1942 2,303,672 Wantz Dec. 1, 1942 2,307,871Wantz Jan. 12, 1943 2,315,773 Couzens Apr, 6, 1943 2,318,136 Alfery May4, 1943 2,318,801 Ray May 11, 1943' 2,353,042 Koch July 4, 19442,383,676 Paille Aug. 28, 1945 2,385,530 Paille Sept. 25, 1945 2,391,753Strobel Dec. 25, 1945 2,409,947 Mantz Oct. 22, 1946 fuel to said mainburner and upon subsequent

